It is helpful to be able to determine conditions at a mobile device, including location and channel quality. Various techniques are known for determining the position of a Long Term Evolution (LTE) user equipment (UE). For example, the location of the serving cell ID (CID) may be used as a rough approximation of the position of the UE; measuring certain network attributes such as round trip time (RTT) and angle of arrival (AOA) may be used to provide more information, known as enhanced cell ID (ECID); and, of course, global positioning system (GPS) or other global navigation satellite systems may be used to determine location. A reference signal time difference (RSTD) may also be used to calculate an LTE observed time difference of arrival (OTDOA). Two OTDOAs is sufficient to calculate the position of a UE. Other TDOA technologies include CDMA AFLT, GSM E-OTD, and WCDMA OTDOA-IPDL. Also, control plane positioning messages may also be exchanged between the network and the UE to determine the position of a UE.
Interference is a common problem in LTE networks. For example, using the 700 MHz band as an example, sources such as television broadcasts, cable television amplifiers, narrow-band radio transmissions and industrial equipment use these legacy channels, and these signals propagate readily across long distances and through building materials, causing interference. Even sources such as light bulb ballasts have been known to generate enough interference in these bands to negatively impact LTE performance. (See FCC File No. EB-FIELDWR-13-00008470.)